Ongoing investigation of the first imported case of Middle East Respiratory Syndrome Coronavirus (MERS-CoV) infection in the United States has identified evidence of apparent past MERS-CoV infection in an Illinois man who had close contact with the Indiana MERS patient. The Illinois resident did not seek or require medical care. However, local health officials have monitored his health daily since May 3 as part of the investigation. At this time, the Illinois resident is reported to be feeling well.

The previously reported Indiana MERS patient is a U.S. resident who had traveled from Saudi Arabia and was admitted to an Indiana hospital on April 28; the patient was confirmed to have MERS on May 2, and has since been released from the hospital.

For the Illinois resident, laboratory test results showing apparent past MERS-CoV infection were reported late night on May 16. CDC officials explained that these laboratory test results are preliminary and suggest that the Illinois resident probably got the virus from the Indiana patient and the person’s body developed antibodies to fight the virus. There are two main ways to determine if a person is or has been infected with MERS-CoV. We can collect a respiratory sample and use a test called PCR to determine if a person has active infection with the virus. Or we can do a blood test that looks for antibodies to MERS-CoV that would indicate a person had previously been infected with MERS-CoV.

“This latest development does not change CDC’s current recommendations to prevent the spread of MERS,” said David Swerdlow, M.D., who is leading CDC’s MERS-CoV response. “It’s possible that as the investigation continues others may also test positive for MERS-CoV infection but not get sick. Along with state and local health experts, CDC will investigate those initial cases and if new information is learned that requires us to change our prevention recommendations, we can do so.”

The Illinois resident has no recent history of travel outside the United States. He met with the Indiana patient on two occasions shortly before the patient was identified as having MERS-CoV infection. As part of the MERS follow-up investigation, the local health department in Illinois contacted the Illinois resident on May 3. The health department first tested this person for active MERS-CoV infection on May 5. Those test results were negative. Public health officials are collecting blood samples from people who were identified as close contacts of the Indiana patient. On May 16, the test result was positive for the Illinois resident, showing that he has antibodies to MERS-CoV.

Reports of the first two confirmed imported cases of MERS in the United States – the first in Indiana on May 2, and the second in Florida on May 11 – have resulted in large-scale multistate investigations and responses aimed at minimizing the risk of spread of the virus. As part of this effort, public health officials are reaching out to healthcare professionals, family members, and others who had close contact with the patients to provide guidance about monitoring their health and recommendations about when to see a healthcare provider for an evaluation. Public health officials also are working with airlines to identify and notify U.S. travelers who may have been exposed to the patient on any of the flights. Efforts are now under way to identify, notify, test, and monitor close contacts of the Illinois resident.

All reported cases of MERS have been linked to countries in and near the Arabian Peninsula. In some instances, the virus has spread from person to person through close contact. However, there is currently no evidence of sustained spread of MERS-CoV in community settings.

At this time, CDC’s recommendations to the public, travelers, and healthcare providers have not changed on the basis of this new information.

For the general public: While experts do not yet know exactly how this virus is spread, CDC routinely advises that people help protect themselves from respiratory illnesses by taking everyday preventive actions like washing their hands often; avoiding touching their face with unwashed hands; avoiding contact with people who appear sick; and disinfecting frequently touched surfaces.

For travelers: CDC currently does not recommend that anyone change their travel plans. If you are traveling to countries in or near the Arabian Peninsula, CDC recommends that you pay attention to your health during and after your trip. The CDC travel notice for MERS-CoV was upgraded to a level 2 alert. The travel notice advises people traveling to the Arabian Peninsula for health care work to follow CDC’s recommendations for infection control, and other travelers to the Arabian Peninsula to take general steps to protect their health.

Healthcare professionals should evaluate patients for MERS-CoV infection who have

(A) fever and pneumonia or acute respiratory distress syndrome, and either

a history of travel from countries in or near the Arabian Peninsula within 14 days before symptom onset, or

have had close contact with a symptomatic traveler who developed fever and acute respiratory illness (not necessarily pneumonia) within 14 days after traveling from countries in or near the Arabian Peninsula, or

are part of a cluster of patients with severe acute respiratory illness of unknown etiology in which MERS-CoV is being evaluated;

(B) or anyone who has had close contact with a confirmed or probable case of MERS while the person was ill, in consultation with state and local health departments.

BackgroundMiddle East Respiratory Syndrome Coronavirus is a virus that is new to humans and was first reported in Saudi Arabia in 2012. As of May 16, there have been 572 laboratory-confirmed cases of MERS in 15 countries. Most of these people developed severe acute respiratory illness, with fever, cough, and shortness of breath; 173 people died. Officials do not know where the virus came from or exactly how it spreads. There is no available vaccine or specific treatment recommended for the virus.